Method and apparatus for forming tablets



Nov. 24, 1964 A. M. RAFF METHOD AND APPARATUS FOR FORMING TABLETS 2 Sheets-Sheet 1 Filed June 6, 1962 7 INVENTOR.

ALLAN M. RAFF g n vfiZ- ATTORNEYS Nov. 24, 1964 A. M. RAFF 3,158,111

METHOD AND APPARATUS FOR FORMING TABLETS Filed June 6, 1962 i 2 sheets sheet 2 4 .x1 w "k i FIG. 3.

I, 14 l| LIG FIG. 4.

INVENTOR.

ALLAN M. RAFF BY t V W ATTORNEYS United States Patent 3,153,111 METHUD AND APPARATUS FOR FGRMLQG TABLETS Allan M. Rad, Elkins Park, Pan, assignor to Smith Kline dz French'liahoratories, Philadelphia, Pa, a 'eorpnratien or Pennsylvania Filed .lnne 6, i962, en. No. 290,463

4 Claims. (El. 107-54) This invention relates to improvement in a method and apparatus for making tablets. Conventionally, in the formation of tablets such as, for example, pharmaceutical tablets, a lubricant is added to the tablet mix which is then placed in a mold cavity and compressed with punch means- The tablet lubricant is necessary to reduce tool wear and to insure that the thus formed. tablet'will not adhere to the mold or punch means and can hence be readily ejected. The presence ofthe tablet lubricant, however, causes a reduction of the cohesiveness of the tablet mix which in turn for a given compressional pressure causes a reduction in desired tablet hardness. Of particular importance with respect to the pharmaceutical tablets, the presence of the.

tablet lubricantrequires the use of increased pressureto achieve the desired tablet hardness and this in turn re-.

sults in an undesirableincrease in the time that it takes the tablet to disintegrate after it has been ingested.

.It is, therefore, the broad object of this invention to provide an apparatus and method giving increased tablet hardness for a given compressional force and to reduce.

the tablet disintegration time by the method and apparatus of this invention. V

In accordance with the method of this invention, the general procedure of forming a tablet by first forming a particular tablet mix, introducing the tablet mix into the mold ofa 'tabletting machine and compressing the mix into a tablet with punch means are employed. However, rather than including the necessary lubricants (as distinguished from agents aiding free flow of the mix) in. the tablet mix in theconventional manner, a tablet lubricant is periodically sprayed on the punch means and the interior of the mold. This permits elimination of al of the tablet lubricant from the tablet Only sufficient lubricant need be sprayed on to provide a substantial covering of the parts which come into contact with the tablet mix. It has been found satisfactory to carry out the spraying once for each about 250 to 30-0 cycles of operation. While the spraing may be carried out more frequently, it is generally not necessary to do so.

The method of this invention is useful with any material which is tabletable by heretofore known methods. Typical, for example, are drugs such as dextroamphetamine sulfate, phenobarbital, chlorphenirarnine maleate, ascorbic acid, atropine sulfate and potassium penicillin which may be combined with other ingredients, for example, fillers such as lactose, dry starch, powdered sucrose, dicalcium phosphate and calcium sulfate dihydrate.

Any of the heretofore known large number of tablet lubricants can be employed in this invention. Thus, for example, powder lubricants, for example, pharmaceutically acceptable metallic soaps such as magnesium stearate or calcium stearate, stearic acid and talc can be employed. Similarly, liquid lubricants, such as butyl stearate or liquid petrolatum may be used. The lubricant advantageously is applied in an aerosol in which the propellant gas may be any of the pharmaceutically acceptable gases frequently empioyed in the aerosol type dispensers such as, for example fiuorinated hydrocarbon derivatives of short chain aliphatic organic compounds such as dichloro-difiuoromethane, dichlorotetrafiuoroethane, octafluorocyclobutane. Further exemplary are com- 1] pressed (non-liquid) gaspropellants such as. nitrous OX- ide, nitrogen, carbon dioxide-and air., The powdered lubricants aresuspended in the liquefied or compressed gas. The powdered lubricant must be substantially insoluble in theselected liquefied gas when ra=liquefied gas is em ployed. The liquid lubricants are dissolved in or'admixed with-the selected gas. Where necessary toprovide a proper gas-lubricant aerosol, theaerosol containor will be agitated periodically. Pressures of frolnabout to about 100 p.s.i.g. at 70 F. aresatisfactoryn The method and apparatus ofthis inventionwill be further clarified-by a reading of the following descriptionin conjunction withthe drawings: 7 FIGURE 1 is a perspective view of arotary tabletting machine incorporating the improvement of the invention; FIGURE-2 'isa plan view partlybroken away of the feed frame ofwthe machine of FIGURE incorporating the. spraying apparatus in accordancewith the invention;

FIGURE?) is'a development of the cam trackswhich control movement of the-punches of the machine-0f FIG-z URE l; and

: FIGURE 4 is a vertical section ratus of this invention.

Referring. to FIGURE 'l, a rotary tabletpressing 'ma chine 2 has a frame4 provided with a base 6; Mounted on frame 4 is-a stationary tablets 'and-a rotating head lil, which rotates clockwise as viewed looking downon it. As best seen inFIGURE 4, head :ltl isconstructed so as to form outwardly extending rings 12,14 and-16:;

Ring 12 is provided with opening 17 toaccommodate upper punches 118.

punch-is then elevated to remove-excess pow'clepwhich is scraped oil. :Thelower punch is then again lowereduntil it is elevated by compressing rollers 34' atwvhich time upper punch 18 which has been elevated is lowered by compressing roller .32 to form the tablet; At 330, the tablet has been liftediout of the'mold andridesofif. the ringi i to be discharged through the chute indicated.

atCin-FIGURELL 1 Referring now to FIGURE, a 38 mounted so as to overlie ring 14 and is provided with walls indicated at 46 41, 4'2, and 43 to form the conventional feed frame grid. A supply hopper 44 is mounted for discharge of the tablet mix onto ring 14 between walls 46 and 41.

As just described, the rotary tablet compressing machine is well-l nown to the art and in wide commercial use today and hence need not be described in any greater detail. For a description of the said tabletting machine, reference may be had, for example, to United States Patent No. 2,043,086, issued June 2, 1936.

Referring now to FIGURE 1, an aerosol container 59 is provided to contain the tablet lubricant and the propellant gas of the aerosol. Container Stl is provided with a control valve structure indicated at'52 which can be used to control the how of the aerosol to line 54 manually when the timer to be described is inoperative. Line a contains a solenoid valve indicated at 55. Valve 55 is connected to a timer schematically indicated at T by through a pair of adjacent dicsillustrating the spraying action of the appa-- Ring 14: is provided with openings 21 to accommodate'molds 22. Ringlis provided with openin s'23 toaccommodate lower punches 24. As best shows a step by step: sequence of the op-f eration' of punches l8 and 24, the degrees marked on the top being arbitrarily chosen'to show the synchronized actionof the parts. At 0,lower punch 24 starts down; opening the mold cavity, -at,about-,- powderis sup-f plied to the. molds for then-filling operation. The lower:

a a line 56 and is connected to ground by a line 57. Timer T is supplied with power by line 58 and is connected to ground by a line indicated at 60. Tirner T can be of any well known type of timer providing an electrical onoff time cycle and will be set to open valve 55 periodically for the time period required for a complete revolution of head -10. While as previously indicated, the frequency of the opening of valve 55 may vary, timer T will be set to open valve 55 at least once for each about 250300 revolutions of head 10. Line 54 discharges into a manifold indicated at 64 (see FIGURE 2) which is secured to frame 38 by welding. Lines 66 and 68 connect manifold 64 to nozzles 73 and 72, respectively. Nozzles 70 and '72 are located on the circumference containing the center line of punches 18 and 24 and on this circumference are located apart the distance separating two adjacent molds 22. The location of nozzles 70 and 72 with relation to the sequential operation of the tabletting machine is shown in FIGURE 3 where the position of these nozzles are indicated by the circles indicated at 70 and 72, respectively. As shown best in FIGURE 4, nozzle 70 is directed downwardly so as to spray the gas-lubricant aerosol into molds 22 and nozzle 72 is directed upwardly so as to direct the spray against punches 18.

It is advantageous to have the punches and interiors of the molds finished with porous chromium plating which retains the lubricant in an improved manner making it possible to apply the lubricant less frequently.

With reference to the previous description of the op eration of the tabletting machine and the showing of FIGURE 3, it will be seen that nozzle 72 is positioned so as to spray punches 18 when they are in their elevated position. Similarly, nozzle 7% is positioned to spray downwardly into molds 22 when punches 24 are fully retracted. It will be appreciated that both spray nozzles are positioned in advance of wall 46 of frame 38 and hence in no way interfere with the filling of mold 22 with the tablet mix.

In operation, the machine 2 is run until timer T is perative to open valve 55 to actuate spraying of the gaslubricant aerosol through nozzles 7t) and 72, timer T keeping valve 55 open during one complete revolution of head 10. The tablet mix free of lubricant is then supplied by means of supply hopper 44 and tablets are produced in the conventional manner. After, for example, 250 revolutions of head 10, timer T actuates valve 55 to spray the aerosol during another complete revolution of head during which revolution tablets will continue to be formed. The operation is repeated until the desired number of tablets are formed.

From the above it will be understood that the method of this invention comprises the steps of forming a tablet in a tablet compressing machine of the type having a mold and punch means adapted to cooperate with the mold wherein the punch means and interior of the mold are periodically sprayed with a tablet lubricant in a spray.

It is not desired to be limited except as set forth in the following claims.

What is claimed is:

l. The steps in the method of forming a pharmaceutical tablet in a tablet compressing machine of the type having a mold and punch means adapted to cooperate with the mold, comprising periodically spraying the punch means and the interior of the mold with a pharmaceutical tablet lubricant in an aerosol spray, repeatedly introducing a pharmaceutical tablet mix substantially free of tablet lubricant into the mold and compressing the mix with the punch means to form a tablet.

2. In a rotating tableting machine having means for rotating a plurality of molds and a plurality of punches for cooperation with said molds, means to feed a tablet mix into the molds, means to retract the punches to permit the feeding of material into the molds and means to advance the punches to compress material fed into the molds, the improvement comprising porous metal plating on the molding surfaces of the punches and the molds for the storage of a lubricant, means including a valve to spray a tablet lubricant on the said molding surfaces with the punches retracted and control means including a timer to maintain the valve normally closed during the rotation of the molds and punches and to periodically open said valve for at least one complete rotation of the molds and punches.

3. The improvement of claim 2 in which the metal is chromium.

4. In a rotating tableting machine having means for rotating a plurality of molds and a plurality of sets of upper and lower punches for cooperation with said molds, means to feed a tablet mix into the molds, means to retract the punches to permit the feeding of material into the molds and means to advance the punches to compress material fed into the molds, the improvement comprising porous chromium plating on the molding surfaces of the punches and the molds for the storage of a lubricant, means including a valve and a pair of nozzles positioned between the plane of the upper ends of the molds and the plane of the retracted lower ends of the upper punches to spray a tablet lubricant on the said molding surfaces with the punches retracted and control means including a timer to maintain the valve normally closed during the rotation of the molds and punches and to periodically open said valve for at least one complete rotation of the molds and punches.

References Cited in the file of this patent UNITED STATES PATENTS 299,514 Brecht June 3, 1884 687,688 Klay Nov. 26, 1901 2,043,086 Westin June 2, 1936 2,638,654 Jordan May 19, 1953 3,029,752 Frank Apr. 17, 1962 

1. THE STEPS IN THE METHOD OF FORMING A PHARMACEUTICAL TABLET IN A TABLET COMPRESSING MACHINE OF THE TYPE HAVING A MOLD AND PUNCH MEANS ADAPTED TO COOPERATE WITH THE MOLD, COMPRISING PERIODICALLY SPRAYING THE PUNCH MEANS AND THE INTERIOR OF THE MOLD WITH A PHARMACEUTICAL TABLET LUBRICANT IN AN AEROSOL SPRAY, REPEATEDLY INTRODUCING A PHARMACEUTICAL TABLET MIX SUBSTANTIALLY FREE OF TABLET LUBRICANT INTO THE MOLD AND COMPRESSING THE MIX WITH THE PUNCH MEANS TO FORM A TABLET. 